Mathematical Operations on Whole Numbers up to 100,000
Primary 4 · Mathematics
Mathematical Operations on Whole Numbers up to 100,000
Lesson 2 of 5
25 min
Let's begin
Keza's mother pays school fees at the bank. On the payment slip she must write the amount twice: once in figures, 32 500 Frw, and once in words. If the words and the figures do not match, the bank will not accept the slip!
Today you will learn to change numbers from figures to words and back again.
The space in a big number splits it into two groups. The group on the left tells you how many thousands. The group on the right is the rest.
| Figures | Left group | Right group | Words |
|---|---|---|---|
| 32 500 | 32 | 500 | thirty-two thousand, five hundred |
| 45 306 | 45 | 306 | forty-five thousand, three hundred and six |
| 70 048 | 70 | 048 | seventy thousand and forty-eight |
| 100 000 | 100 | 000 | one hundred thousand |
Zeros are silent: we never say "zero hundreds". Use a hyphen for numbers like twenty-one to ninety-nine: thirty-two, forty-eight.
Do it in two steps. Write the thousands, then write the rest using exactly three digits.
Sixty thousand and nine: the thousands are 60. The rest is 9, which we write with three digits as 009. So the number is 60 009.
A common mistake is to write 600 009. That number has too many digits! After the thousands group there are always exactly three digits.
Tip
Three after the space. In a number up to 100 000 there are always exactly three digits after the space. If you have fewer, fill the empty places with zeros.
Work each one in your exercise book first. Then tap Show answer to check.
Write 27 815 in words.
Answer: twenty-seven thousand, eight hundred and fifteen
Write in figures: fifty-four thousand, two hundred and six.
Answer: 54 206
Write in figures: ninety thousand and seventy.
Answer: 90 070. The thousands are 90; the rest is 70, written as 070.
Write 100 000 in words.
Answer: one hundred thousand
Gatete wrote "eight thousand and five" as 80 005. Is he right?
Answer: No. Eight thousand and five is 8 005. His number, 80 005, is eighty thousand and five.
What you learned today
Sources and credits
The stories, Rwandan worked examples, diagrams and practice questions were written by Ganzaa.
Quick check
Write forty-three thousand and nine in figures.
