# DAY 311: The Main Challenge

Further details of my popular Mathelona number puzzle can be found by clicking this Mathelona link.

Can you make all four lines work out arithmetically by filling the 16 gaps below with digits 0-9? Each digit can only be inserted a maximum of TWICE:

◯  +  ◯   =    9    =   ◯  +  ◯
◯  +  ◯   =    9    =   ◯  –  ◯
◯  +  ◯   =    9    =   ◯  ×  ◯
◯  +  ◯   =    7    =   ◯  ÷  ◯

Were you able to complete this without repeating the same sum when making 9? The 7puzzle Challenge

The playing board of the 7puzzle game is a 7-by-7 grid containing 49 different numbers, ranging from 2 up to 84.

The 2nd & 5th rows contain the following fourteen numbers:

6   7   8   16   17   21   28   48   50   55   63   64   81   84

How many factors of 48 are listed? The Factors Challenge

Which of the following numbers are factors of 311?

3     5     7     9     11     13     None of them The Mathematically Possible Challenge

Using 47 and 11 once each, with + – × ÷ available, which are the only TWO numbers it is possible to make from the list below?

7    14    21    28    35    42    49    56    63    70

#7TimesTable The Target Challenge

Can you arrive at 311 by inserting 1, 2, 3, 4 and 5 into the gaps below?

•  (◯³×◯)–(◯⁴×◯×◯) = 311   