Three-digit whole numbers like 154 and 275 have the property that the first digit plus the last digit equals the middle digit (1 + 4 = 5, 2 + 5 = 7). How many three-digit whole numbers have this property?

Question

Accepted Answer

45. Let the digits be a (hundreds, 1 to 9), b (tens), c (units). We need a + c = b with b at most 9. For each first digit a from 1 to 9, c can be 0, 1, ..., up to 9 - a, giving 10 - a choices. Total = 9 + 8 + 7 + ... + 1 = 45.

Three-digit whole numbers like 154 and 275 have the property that the first digit plus the last digit equals the middle digit (1 + 4 = 5, 2 + 5 = 7).
How many three-digit whole numbers have this property?

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More Class 6 Properties of Whole Numbers practice

Three-digit whole numbers like 154 and 275 have the property that the first digit plus the last digit equals the middle digit (1 + 4 = 5, 2 + 5 = 7).How many three-digit whole numbers have this property?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 6 Properties of Whole Numbers practice

Three-digit whole numbers like 154 and 275 have the property that the first digit plus the last digit equals the middle digit (1 + 4 = 5, 2 + 5 = 7).
How many three-digit whole numbers have this property?