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Subtracting (43 − 16)
Textbook: Part 1, lesson 28, pp. 60–61
GoalLearn subtracting a two-digit number from a two-digit number with regrouping (43 − 16).
New words
minuend · kamayuvchisubtrahend · ayriluvchipainter · rassomhall · zal
Explanation
We cannot take 6 from 3 ones. We break 1 ten from 4 tens: 3 tens 13 ones − 1 ten 6 ones = 2 tens 7 ones = 27. Check: 27 + 16 = 43.
Worked examples
31 − 16 = 2 tens 11 ones − 1 ten 6 ones = 1 ten 5 ones = 15.
44 − 25 = 3 tens 14 ones − 2 tens 5 ones = 19.
Class activity
“Ten exchange”: show 43 − 16 with cubes: one of the 4 ten-rods is exchanged for 10 single cubes.
Practice
1
26 − 17 = ?
9
2
37 − 28 = ?
9
3
44 − 25 = ?
19
4
A painter drew 30 colour and 15 black-and-white pictures on day 1 and 28 on day 2. How many fewer on day 2?
17