56
Subtracting three-digit numbers
Textbook: Part 2, lesson 54, pp. 28–29
GoalSubtracting from round numbers: 100 = 9 tens 10 ones.
New words
round number · yaxlit sonten · o‘nlikexchange · almashtirishwhat is left · qoldiq
Explanation
To subtract from 100 we trade the hundred for 10 tens, then one ten for 10 ones: 100 = 9 tens 10 ones. 100 − 36: 9 tens − 3 tens = 6 tens, 10 ones − 6 ones = 4 ones – the answer is 64. 700 − 267 works the same way: 700 = 6 hundreds 9 tens 10 ones.
Worked examples
100 − 82 = 18, because 82 + 18 = 100.
500 − 478: 4 hundreds 9 tens 10 ones − 4 hundreds 7 tens 8 ones = 22.
Class activity
“Break the hundred”: with 100 sticks (10 bundles of 10) children solve 100 − 55 by breaking bundles apart and showing the leftovers.
Practice
1
100 − 36 = ?
64
2
700 − 267 = ?
433
3
400 − 182 = ?
218
4
900 soft cubes were brought to a pool, 465 of them blue and the rest green. How many are green?
435