Mathematics | Class: JSS1 | Term: 1st

Rounding Off Numbers

len Alfred Ajibola - 01st February, 2026 @ 09:22 PM

Topics in Mathematics

Linear Equation in Mathematics Word Problems leading to Algebraic Expression BODMAS in Algebra Multiplication and Division in Algebra Addition and Subtraction in Algebra Multiplication of Number Bases Subtraction of Number Bases Addition of Number Bases Division of Number Base Number Base Conversion Number Base System Significant Figures Rounding Off Numbers Decimal Place Value Fraction Word Problems Word Problems in Fraction Multiplication and Division of Fractions Addition and Subtraction of Fractions Expressing One Quantity as a Percentage of Another Expressing One Quantity as a Fraction of Another


Academic Questions in Mathematics

Please click here to see all Questions and Answers

Decagon - Len Academy

What type of polygon is shown in the above image?

  • A. Nonagon

  • B. Decagon

  • C. Octagon

  • D. Hexagon

  • E. Hepagon

  • F. Pentagon

Which of the following is not part of a circle?

  • A. Section

  • B. Sector

  • C. Segment

  • D. Semicircle

  • E. Secant

  • F. Center

Acute Angle - Len Academy

What angle is shown in the above image?

  • A. Complementary

  • B. Supplementary

  • C. Acute

  • D. Obtuse

  • E. Reflex

  • F. Straight

An angle greater than 90o but less than 180o is termed _____.

  • A. Complementary

  • B. Supplementary

  • C. Acute

  • D. Obtuse

  • E. Reflex

  • F. Straight

Factorize 12a2 - 20a + 3

  • A. (6a - 1)(2a - 3)

  • B. (6a - 1)(2a + 3)

  • C. (6a + 1)(2a - 3)

  • D. (6a + 1)(2a + 3)

  • E. (-6a + 1)(2a - 3)

  • F. (-6a + 1)(2a + 3)

Simplify 10ab + 7ab

  • A. 17ab2

  • B. 17a2b2

  • C. 3ab2

  • D. 3a2b2

  • E. 17ab

  • F 3ab

Which of the following is not a type of angle?

  • A. Right angle

  • B. Left Angle

  • C. Acute Angle

  • D. Complete Angle

  • E. Straight Angle

  • F. Reflex angle

Two lines that can never meet each other are best considered as _____ lines.

  • A. straight
  • B. vertical
  • C. horizontal
  • D. parallel
  • E. oblique
  • F. perpendicular



Rounding Off Numbers


Rounding off numbers in mathematics refers to the simplification of numbers to a nearby value by targeting their place value, and adjusting the number accordingly, replacing digits to the right with zeros for whole numbers (or dropping them for decimals), such that its value remains close to what it was, thus making them easier to use.

Below are the basic rules for rounding off numbers:

  • Identify the place value you want to round to (e.g. thousands, hundreds, tens, tenths, hundredth, thousandths and so on).

  • Look at the digit immediately to the right of that place value. If this digit is 5 or greater (that is: 5, 6, 7, 8, 9): Round up by increasing the target digit (to the left) by one)

  • If the digit is 4 or less (that is: 4, 3, 2, 1, 0), Round down by leaving the target digit (to the left) just the way it was.

Please read on place value of numbers here.

When rounding off whole numbers, adjust the digits to the right by changing them to zeros. For decimals, drop them.

 

An understanding on the concept of thousands, hundreds, tens, unit, tenth, hundredth, thousandth, and so on are crucial in place values. This is summarized via the image below:

Place Values of Numbers - Len Academy

Please read on the factors of numbers here.

Please read on decimal places here.

 


Worked Examples on Rounding Off Numbers


Example 1
  • Approximate 179.734 to the nearest:

  • Hundred

  • Ten

  • Whole number

  • Tenth

  • Hundredth 

Solution

Note: If the digit immediately after the place value is 5 or greater, round up by adding 1. If lesser than 5, round down be leaving the value as it were.

179. 734

To nearest hundred, digit of importance is 1

  • 179.734 = 200 (nearest hundred)

To nearest ten, digit of importance is the 'first' 7

  • 179. 734 = 180 (nearest ten)

To whole number, digit of importance is the value before the decimal place, and that's 9.

  • 179. 734 = 180 (nearest whole number)

To nearest tenth, digit of importance is the 'second' 7

  • 179.734 = 179.7 (nearest tenth)

To nearest hundredth, digit of importance is 3

  • 179.734 = 179.73 (nearest hundredth)

 

Example 2
  • Round off 567 to the nearest ten

Solution 

To nearest ten, digit of importance is 6

  • 567 = 570 (nearest ten)

 

Example 3
  • Round oof 39976 to the nearest hundred.

Solution 

To nearest hundred, digit of importance is the "second" 9.

  • 39976 = 40,000 (nearest hundred)

 

Example 4:
  • Round off 56489 to the nearest thousand.

Solution 

To nearest thousand, digit of importance is 6

  • 56489 = 56000 (nearest thousand)

 

Example 5
  • Round off 3.025 to the nearest unit.

Solution

To nearest unit, digit of importance is 3

  • 3. 025 = 3 (nearest unit )

 

Example 6
  • Round off 16.95 to the nearest tenth

Solution 

To nearest tenth, digit of importance is 9

  • 16.95 = 17.0 (nearest tenth)

 

Example 7
  • Round off 7089.0957 to the nearest hundredth

Solution 

To nearest hundredth, digit of importance is the 9 after the decimal place.

  • 7089.0957 = 7089.10 (nearest hundredth).

 

Example 8
  • Round off 1808.9745 to the nearest thousandth

Solution 

To nearest thousandth, digit of importance is 4.

  • 1808.9745 = 1808.975 (nearest thousandth).

Please read on the conversion of decimals to fractions here.

Please read on significant figures here.

 


Assignment on Rounding Off Numbers


Round off the following numbers:

  • 345 to the nearest tens

  • 375 to the nearest tens

  • 695 to the nearest tens

  • 705 to the nearest tens

  • 715 to the nearest tens

  • 6.1 to the nearest whole number

  • 13.3 to the nearest whole number

  • 78.75 to the nearest whole number

  • 26.9 to the nearest whole number

  • 9.5 to the nearest whole number

  • 0.71 to the nearest tenth

  • 0.01 to the nearest tenth

  • 0.15 to the nearest tenth

  • 0.45 to the nearest tenth

  • 0.98 to the nearest tenth

  • 0.614 to the nearest hundredth

  • 0.617 to the nearest hundredth

  • 0.706 to the nearest hundredth

  • 0.702 to the nearest hundredth

  • 0.295 to the nearest hundredth

Please read on mathematics week 7 topic for jss1 first term here.

Please read on mathematics scheme of work for jss1 first term here.

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Amazing facts in Mathematics

The opposite sides of a dice will always give a sum of seven

31,556,926 seconds makes one year

From 0 through 1000, the only number that has the letter 'a' in it is 'one thousand'

÷

The division symbol '÷' is actually called an obelus

Four is the only number in the English language that is spelt with the same number of letters as the number (4) itself

40 is spelt as forty and not 'fourty'. It is the only number that is spelt with letters arranged in alphabetical order

An odd number is a number that cannot be divisible by 2.

Every odd number has an 'e' in its spelling. They include:

  • One
  • Three
  • Five
  • Seven
  • Nine

555 in Thailand sounds like 'hahaha'. This is because the number '5' means 'ha' in Thailand

In mathematics, 10! means 10 factorial. Below is its calculation:

10! = 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 3628800

Interestingly, 3628800 seconds is the same as 42 days

42 days is the same as 6 weeks

We can therefore say that 10! equals 6 weeks or 3628800 seconds in mathematics

When you multiply 111,111,111 by 111,111,111; the result equals 12,345,678,987,654,321


Notable points in Mathematics

Let's use algebra to explain the simple statement below:

I am a number. When you subtract 3 from me, the result is 9. what number am I ?

Of course we know the answer is 12. You probably guessed it from your mind because it was that simple. The truth is, We could have a much more complicated statement of such; and that is where algebra comes into play.

Now, to apply algebra in the above statement, we use letters or alphabets to represent the unknown number(s). So using algebra, we can write:

  • Let the number be y

  • y - 3 = 9

  • y = 9 + 3

  • y = 12

Please read more on algebra here

Sides of a right angle triangle - Len Academy

 

The image above shows a right angled triangle. The angle of the above right triangle is denoted as θ. Below are some points to note:

Hypotenuse is always the longest side of the triangle.

Opposite is the side opposite the angle (θ)

Adjacent is the shorter side next to the angle (θ)

Each of Sin θ, cos θ and tan θ are the ratio of sides of the right triangle. They are calculated by using the formula (margic word) sohcahtoa:

Sohcahtoa - Len Academy

soh

Sin θ = Opposite/Hypotenuse

cah

Cos θ = Adjacent/Hypotenuse

toa

Tan θ = Opposite/Adjacent

Please read more on sine, cosine and tangent here

Circumference of a Circle - Len Academy

Circumference in mathematics means the distance around the edge of a circle (or a another curved surface).

Circumference is to circle or any other curved surface

Perimeter of a Rectangle - Len Academy

Perimeter means the distance around a square or rectangle or polygon.

Perimeter is to square or rectangle or polygon