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Subtracting two-digit numbers (practice)
Textbook Part 2, pp. 56–57
Goal“... fewer” problems; writing inequalities; number chains.
New words
... fewer · ... ta kam... more · ... ta ko‘pinequality · tengsizlik
Explanation
When a problem says “... fewer”, we usually subtract; “... more”, we add. We write inequalities with signs: “16 is greater than 13” → 16 > 13.
Worked examples
School 1 collected 43 sacks of acorns for the Bukhara deer; school 2 collected 12 sacks fewer: 43 − 12 = 31 sacks.
Chain (each 11 more than the last): 12, 23, 34, 45, 56.
Class activity
“Bells”: each bell has a number. Children write it as tens plus ones (e.g. 57 = 50 + 7) and then subtract 12 from it.
Practice
1
43 − 12 = ?
31
2
Continue the chain (each 12 fewer): 98, 86, 74, _, _
62, 50
3
Write with a sign: “15 is less than 20”.
15 < 20
4
99 − 55 = ?
44