Question

Steve will write the list of consecutive integers, starting with 1, at the speed of 5 digits per second. What will be the sum of the final two digits he writes on his list at the end of 10 seconds?

Answer 1

12.

Explanation:

If he writes 5 digits a second, then in 10 seconds he will write 50 digits:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 3

9 + 3 = 12

Hope this help!

Answer 2

Answer: 12

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Work Shown:

5 digits = 1 second

50 digits = 10 seconds (multiply both sides by 10)

At the end of 10 seconds, he has written 50 digits.

The first 9 digits (1 through 9) are single digits. After writing them, Steve has 50-9 = 41 digits left.

41/2 = 20 remainder 1. So this means that he wrote 20 additional two-digit numbers after that 1 through 9 block of single digit numbers. Those two-digit numbers are 10 through 29. The last digit he writes is 3

So the last two digits he wrote was 9 and 3

Add them up get 9+3 = 12