Why ZZ = (10×Z)+Z when Z = 4

Question

I started to learn mathematical fundamentals course at brilliant.org and there is a puzzle

Maybe is too late or I just don't get it, why is

ZZ = (10×Z)+Z

and how they get this equation from the question ? Because the formula does not even fit, but leads to a successful solution, I'm confused.

4 x 4 != (10 x 4) + 4 
16 != 44

score 2 · Accepted Answer · answered Apr 11 '20 at 00:27

2

When they write "ZZ", it means a number like 33, 44, 55, etc. where it's just two digits repeated.

Writing two letters together in elementary algebra implies multiplication. But in our base-ten system (ones, tens, hundreds, thousands, etc.), that means TEN times the digit in the TENS digit, plus ONE times the digit in the ONES digit.

answered Apr 11 '20 at 00:27

The Chaz 2.0

10,464

1

I got it, thank you ! :D – Muflix Apr 11 '20 at 00:43

Why ZZ = (10×Z)+Z when Z = 4

1 Answers1