How many two-digits numbers have a second digit greater than the first digit?
Answers
Answer:
Assuming that the second digit means the second number you type or write manually from left to right, it’s 36. That’s the first group. But, I can’t just assume that is the case. If you count (not add) all the two digit-numbers below, you’ll get thirty six. This is true for any two-digit counting numbers (zero not included) regardless which position is meant by “second digit greater than the first”.
ANSWER: Thirty six two digit numbers with the “second digit greater than the first digit” are listed below in two groups.
First Group
12 13 14 15 16 17 18 19
23 24 25 26 27 28 29
34 35 36 37 38 39
45 46 47 48 49
56 57 58 59
67 68 69
78 79
89
Second Group
98 97 96 95 94 93 92 91
87 86 85 84 83 82 81
76 75 74 73 72 71
65 64 63 62 61
54 53 52 51
43 42 41
32 31
21