A positive integer is called a rising number If its digits form a strictly increasing sequence. for example, 1457 is a rising number, 3438 is not a rising number, and neither 2334.

Question

A positive integer is called a rising number If its digits form a strictly increasing sequence. for example, 1457 is a rising number, 3438 is not a rising number, and neither 2334.
Questions: How many 3-digit rising numbers are there where 3 is the middle digit? (solved) How many three-digit rising numbers are there?

bobpursley · Answer

x3y : x can have 2 values, y can be six, so there are 12 rising numbers. How many three-digit numbers, 9*10*10= ?

scott · Answer

the 1st part of the question is a BIG hint for the 2nd part sum the 1st part solutions for the digits 2 through 8