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Number Detective

Follow the clues to find the mystery number.

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?


In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?

Song Book

Age 7 to 11
Challenge Level

A school song book contains 700 songs, numbered 1 to 700.

Each month at a special assembly, the children sing four different songs.

The numbers of the songs are displayed to the children by putting together single-digit cards like this:


The card for 6 may be turned upside down to serve as a 9.

What is the minimum number of digit cards that is needed to show any possible combination of four song numbers?

How many of each digit must there be?