# DAY 18:

Today’s Challenge

The numbers 21 to 29 inclusive must be allocated to each letter below so that each number satisfies the condition given on the line and only appears once:

• (a) even number,
• (b) factor of 144,
• (c) power of 3,
• (d) prime number,
• (e) digits which differ by 1,
• (f) exactly 3 factors,
• (g) multiple of 7,
• (h) equal to the sum of all its factors (except the number itself),
• (i) 2nd digit is greater than its 1st digit.

Remember, the numbers 21 to 29 should only appear once each.

The 7puzzle Challenge

The playing board of the 7puzzle game is a 7-by-7 grid containing 49 different numbers, ranging from up to 84.

The 1st & 7th rows of the playing board contain the following fourteen numbers:

2   4   9   11   14   15   22   24   27   30   40   70   72   77

Which odd number, when 21 is added to it, becomes a square number?

Make 18 Challenge

Can you arrive at 18 by inserting 2, 3, 4 and 6 into the gaps on each line?

•  ◯×◯–◯×◯ = 18
•  ◯÷◯×◯×◯² = 18
•  (◯÷◯)³×√◯÷◯ = 18