Asked by Biscuit

In how many whole numbers between 100 and 999 is the middle digit equal to the sum of the other two digits?
Answered by Steve
45

Here's why:
If first digit is k, middle is k+i, last is i.

Max k+i is 9, so i ranges from 0 to 9-k

So, there are
9 numbers starting with 1,
8 starting with 2,
...
1 starting with 9

sum of numbers from 1 to 9 is 9*10/2 = 45
Answered by Anonymous
45
Answered by ALEX
I LOVE MATHS 5+5=10


































































































Answered by Alice
45
Answered by Ransa
How many whole numbers between 100 and 999 have their digits in strictly decreasing order
Answered by Nick
198
Answered by anon.
53. Easy.
Answered by Reeet
ZXedv3c1 niol8
Answered by Oscar
45 btw do u like Olivia Rodrigo?
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