Posted by Mildred on Monday, October 19, 2009 at 11:20pm.
what is a?
Sorry,
a) 10 and 400
b) 10 and 1000
im not sure im typing as i find them.
A=total of counting the numbers 11,22,33,44,55,66,77,88,99,101,202,303
B) = total counting the numbers
11,22,33,44,55,66,77,88,99,101,202,303,404,505,606,707,808,909
Mark is right, but for numbers of the form x0x, you can of course use any digit, not just zero, so
101
also implies
111, 121, 131,....