# DAY/DYDD/PÄIVÄ/NAP 15 The Main Challenge

Your task is to multiply two numbers together and then subtract a third number to achieve the target answer of 7. The three numbers used in each calculation must all be unique digits from 1-9.

For example, one such way of making 7 is (4×3)5. Can you find SIX other ways to make 7?

[Note:  (4×3)5 = 7  and  (3×4)5 = 7  counts as ONE way.] 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 5th & 6th rows contain the following fourteen numbers:

5   6   7   12   16   18   20   21   33   49   50   56   81   84

What is the difference between the total of the prime numbers and the sum of the multiples of 10? The Lagrange Challenge

Lagrange’s Four-Square Theorem states that every positive integer can be made by adding up to four square numbers.

For example, 7 can be made by 2²+1²+1²+1² (or 4+1+1+1).

There is only ONE way of making 15 when using Lagrange’s Theorem. Can you find it? The Mathematically Possible Challenge

Using 56 and once each, with + – × ÷ available, which is the ONLY number it is possible to make from the list below?

5    10    15    20    25    30    35    40    45    50

#5TimesTable

The Target Challenge

Can you arrive at 15 by inserting 2, 3, 5 and 6 into the gaps on each line?

•  ◯×◯+◯◯ = 15
•  ◯÷×²×◯ = 15
•  ◯²–(◯+◯)× = 15 Answers can be found here. Click Paul Godding for details of online maths tuition. This entry was posted in 7puzzleblog.com. Bookmark the permalink.

This site uses Akismet to reduce spam. Learn how your comment data is processed.