54
Subtracting three-digit numbers
Textbook: Part 2, lesson 52, pp. 24–25
GoalSubtract three-digit numbers place by place; borrow from the next place when needed.
New words
minuend (number we subtract from) · kamayuvchisubtrahend (number we subtract) · ayriluvchidifference · ayirmaborrowing · qarz olish (ochish)
Explanation
We subtract place by place. If there are not enough ones, take 1 from the next bigger place and change it into 10 of this place. 456 − 173: ones 6 − 3 = 3; tens – we cannot take 7 from 5, so borrow 1 hundred: 15 − 7 = 8; hundreds 3 − 1 = 2. The answer is 283.
Worked examples
143 − 50 = 93: 14 tens − 5 tens = 9 tens, and 3 ones stay.
762 − 245: 12 − 5 = 7, 5 − 4 = 1, 7 − 2 = 5 → 517.
Class activity
“Let’s borrow”: subtract with a model of ones-cubes, tens-sticks and hundreds-plates. Children trade one piece from the next place for 10 smaller pieces where there are not enough.
Practice
1
143 − 50 = ?
93
2
456 − 173 = ?
283
3
762 − 245 = ?
517
4
A museum has 977 items, 492 of them gold-thread embroidery. How many are the rest?
485