Anya writes three-digit numbers whose three digits, read in order, are consecutive whole numbers increasing by 1, like 123, 234, 345 (so 8 and 9 cannot be followed since the next digit would exceed 9). How many such three-digit numbers can she write?

Question

Accepted Answer

7. The first digit can be 1,2,3,4,5,6,7 (it must be at least 1 and the third digit first+2 must be at most 9, so first <= 7). That gives 123, 234, 345, 456, 567, 678, 789 = 7 numbers.

Anya writes three-digit numbers whose three digits, read in order, are consecutive whole numbers increasing by 1, like 123, 234, 345 (so 8 and 9 cannot be followed since the next digit would exceed 9).
How many such three-digit numbers can she write?

Step-by-Step Solution

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More Class 6 Patterns in Whole Numbers practice

Anya writes three-digit numbers whose three digits, read in order, are consecutive whole numbers increasing by 1, like 123, 234, 345 (so 8 and 9 cannot be followed since the next digit would exceed 9).How many such three-digit numbers can she write?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 6 Patterns in Whole Numbers practice

Anya writes three-digit numbers whose three digits, read in order, are consecutive whole numbers increasing by 1, like 123, 234, 345 (so 8 and 9 cannot be followed since the next digit would exceed 9).
How many such three-digit numbers can she write?