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即39+5用加九法

2006-11-20 16:59:26 · 2 個解答 · 發問者 CHRIS 1 in 科學 數學

2 個解答

39+5=40-1 + 5=(40+5)-1=44
Memorize
9=10-1
8=10-2
7=10-3
6=10-4
5=10-5
4=10-6
3=10-7
2=10-8
1=10-9

47+26=50+26-3=73

2006-11-21 06:59:33 · answer #1 · answered by p 6 · 0 0

39+5=(40-1)+5=40+5-1=45-1=44

2006-11-21 06:57:19 · answer #2 · answered by Tom 2 · 0 0

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