How Numbers are Round Off

How Numbers are Round off

Working with longer number may likely to get you in confusion, rounding number and eliminating some is the best path mathematician do follow. Also when working with some problems you may be asked to round off your answer.

Rounding number helps you change some of it digit to place-holding zeros or change a difficult number to an easier one. Stick to the information below to avoid some mistakes.

Rounding to the nearest ten

When rounding a two-digit numbers to the nearest ten, bring it up or down to the nearest number which ends in 0

Examples

    1. 45 → 40
    2. 54 → 50
    3. 22 → 20
    4. 75 → 80
    5. 73 → 70
    6. 92 → 90.
Higher than or equal to 95
    7. 95 → 100
    8. 97 → 100
    9. 98 → 100
    10. 96 → 100.

No matter higher the number ends. Except for numbers higher than 95`s which round up to 100.

Rounding to the nearest hundred

To round number to the nearest hundred and beyond the focus on the hundreds digit and the digit immediate right of the hundreds digit, change all other digits to the right of these two-digit to 0`s.

Examples

    1. 899 → 900
    2. 354 → 400
    3. 540 → 500
    4. 795 → 800
    5. 952 → 1000.

Note: if the number immediate the hundreds digit is five or higher (5, 6, 7, 8, 9) change it to 1 and add it to the hundreds digit, but if it four or lower (4, 3, 2, 1 ) it will be 0.

Rounding to the nearest thousand

Underline the thousand digit and the digit immediate right, change all the other digit to zero (digit greater than or equal to 5 changes to 1 and add to the thousands digit, digit less than or equal to 4 changes to 0).

Examples

    1. 4,372 → 4,000
    2. 7,535 → 8,000
    3. 6,683 → 7,000
    4. 78,521 → 79,000
    5. 7,891 → 8,000.

Rounding to the nearest million

Rounding to million also follows the same rule only you focus on the millions digit and the digit immediate the millions.

Examples

    1. 1,234,567 → 1,000,000
    2. 85,923,531 → 86,000,000
    3.2,535,253 → 3,000,000.

Problem easier with Approximating value

After you have bet down rounding, Approximating number is simple, it saves much of your time while calculating and allow you to avoid complicated calculation. Approximately equal to( ≈ ) is used instead of equal sign =. In some cases, if you approximate a given numbers before calculating the real answer, it could result in the round off answer, but sometimes it works. I will only advise you to approximate at the end of your answer especially if you are told to do so in the question.

Examples:

    1. 722 + 506 + 383 + 1,279 + 91 + 811,
round this number down, 
700 + 500 + 400 + 1300 + 90 + 800
≈ 3,800.

But if you add without rounding the answer is 3,792, which is not a bad answer (because if you round the answer you will still get 3,800).

Also, check this out.
879 x 618  if round off, it changes to 900 x 600. Which equals 540,000 (good answer, you will think it is) but if you did not round off before the multiplication takes place, the answer will be 543,222.

You can see that...

A Little advice on approximating number that can help, not getting round off answer.
 Don`t round too many numbers in the same direction.
Don`t multiply or divide rounded numbers.