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Six Is the Sum

What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

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(w)holy Numbers

A church hymn book contains 700 hymns. The numbers of the hymns are displayed by combining special small single-digit boards. What is the minimum number of small boards that is needed?

Reach 100

Stage: 2 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Simply writing out the numbers $1 - 9$ along the top of your paper can be a great help.

Imagine arranging your four two-digit numbers in columns to do the addition sum, like this:

$5 \: 2$
$1 \; 9$
$5 \; 1$
$2 \; 9$

If the total has to be $100$, think about how the four digits you choose could add to make the $0$ in the units column, then look at the tens column.