Mathematical Operations on Whole Numbers up to 100,000
Primary 4 · Mathematics
Mathematical Operations on Whole Numbers up to 100,000
Lesson 1 of 5
25 min
Let's begin
Umutoni's family belongs to an ikimina, a savings group. At the end of the month the group counts its money: 45 306 Frw. Umutoni looks at the 4 at the front and asks, "Is that 4 francs or 4 thousand francs?"
The answer depends on the place where the 4 sits. In this lesson you will learn to read every place in numbers up to 100 000.
Count in thousands: 7 000, 8 000, 9 000, 10 000. Ten thousands make ten thousand (10 000).
Now count in ten thousands: 10 000, 20 000, 30 000 … 90 000, 100 000. Ten ten-thousands make one hundred thousand (100 000).
Notice the pattern: each place is worth ten times the place on its right. 10 ones make a ten, 10 tens make a hundred, and so on all the way up.
We write big numbers in groups of three digits from the right, with a small space between the groups: 45 306. Some books use a comma instead: 45,306. Both mean the same number.
| Hundred thousands | Ten thousands | Thousands | Hundreds | Tens | Ones |
|---|---|---|---|---|---|
| 4 | 5 | 3 | 0 | 6 |
The place value of a digit is the name of its place. The value is how much the digit is worth there.
So the ikimina has forty thousand francs, not four!
We can break a number into the values of its digits:
45 306 = 40 000 + 5 000 + 300 + 6
Keza has five digit cards: 7, 0, 3, 9, 5.
Tip
Read the place, then the digit. Put your finger on a digit and walk right to count the places after it. Four places after it? It is in the ten thousands place, so multiply it by 10 000.
Work each one in your exercise book first. Then tap Show answer to check.
What is the value of the 7 in 57 214?
Answer: 7 000. The 7 is in the thousands place.
Write 60 000 + 8 000 + 90 + 4 as one number.
Answer: 68 094. There are no hundreds, so a 0 holds the hundreds place.
In 83 516, which digit is in the ten thousands place?
Answer: 8
Use the digits 4, 1, 8, 0 and 6 once each. Make the largest and the smallest five-digit number.
Answer: Largest 86 410; smallest 10 468 (it cannot start with 0).
What number is 1 000 more than 39 500?
Answer: 40 500. The thousands go from 9 to 10, so the ten thousands grow by one.
What you learned today
Sources and credits
The stories, Rwandan worked examples, diagrams and practice questions were written by Ganzaa.
Quick check
What is the value of the 6 in 36 418?
