HOW MANY NUMBERS FROM 10 TO 99 HAVE SUM OF THEIR DIGITS EQUAL TO 9
Câu 7: How many numbers from 10 to 99 have sum of their digits equal to 9?
a) 10
b) 20
c) 18
d) 9
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Câu 7: How many numbers from 10 to 99 have sum of their digits equal to 9?
a) 10
b) 20
c) 18
d) 9