A problem by Vraj Mistry
Level
pending
Right across the street is a fast food outlet that sells chicken in the order of 6, 9 and 20 only. Determine the maximum number of chicken pieces that cannot be ordered from the outlet?
The answer is 43.
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1 solution
43
Let us break the problem into different parts. We know that after six, all the numbers that are divisible by three can be ordered. This is because we can expand them as the sum off sixes and nines. After twenty six, the numbers that are divisible by three if subtracted by twenty can also be ordered. After forty six, all the numbers will fit in one of the already discussed category. Thus all the numbers can be ordered. So forty three is the last number that does not come under any of the already discussed category. 44 = 20 + 6 * 4, 45 = 6 * 6 + 9