Mathematical Operations on Whole Numbers up to 100,000
Primary 4 · Mathematics
Mathematical Operations on Whole Numbers up to 100,000
Lesson 3 of 5
25 min
Let's begin
Two coffee cooperatives in Huye sold coffee last month. Cooperative A earned 48 750 Frw and Cooperative B earned 48 570 Frw. The numbers use the same digits! Which cooperative earned more?
A number with more digits is bigger. 10 002 has five digits and 9 876 has only four, so 10 002 is bigger.
If both numbers have the same number of digits, start at the biggest place and move right until the digits are different.
| TTh | Th | H | T | O | |
|---|---|---|---|---|---|
| A | 4 | 8 | 7 | 5 | 0 |
| B | 4 | 8 | 5 | 7 | 0 |
The ten thousands are the same (4). The thousands are the same (8). The hundreds are different: 7 hundreds is more than 5 hundreds. So 48 750 is greater than 48 570. Cooperative A earned more.
On a number line, the bigger number is always further to the right.
Ascending order goes from the smallest to the largest, like climbing up a hill. Descending order goes from the largest to the smallest, like walking down it.
Put 36 402, 63 204, 36 240 and 34 620 in ascending order. Compare the ten thousands first: only 63 204 starts with 6, so it is the largest. The others all start with 3, so look at the thousands: 34 620 is the smallest. Then 36 240 < 36 402 because 2 hundreds < 4 hundreds.
Ascending order: 34 620, 36 240, 36 402, 63 204.
Tip
The hungry crocodile. The open mouth of < or > always faces the bigger number, because the crocodile wants to eat the bigger meal!
Work each one in your exercise book first. Then tap Show answer to check.
Write <, > or = : 72 391 ___ 72 319
Answer: >. The tens are different: 9 tens is more than 1 ten.
Write <, > or = : 9 876 ___ 10 002
Answer: <. A four-digit number is less than a five-digit number.
Write <, > or = : 50 000 + 400 + 3 ___ 50 403
Answer: =. Both sides are fifty thousand, four hundred and three.
Put in ascending order: 45 120, 41 520, 45 012, 54 210.
Answer: 41 520, 45 012, 45 120, 54 210
Put in descending order: 80 808, 88 080, 80 880, 88 800.
Answer: 88 800, 88 080, 80 880, 80 808
What you learned today
Sources and credits
The stories, Rwandan worked examples, diagrams and practice questions were written by Ganzaa.
Quick check
Which sign goes in the gap? 63 518 ___ 63 581
