Consecutive Numbers


Andrew and Tom sent this in to us:

Numbers 14, 15, 16, 17:

1, 14 + 15 + 16 + 17 = 62
2, 14 - 15 - 16 - 17 = -4
3, 14 + 15 - 16 + 17 = 30
4, 14 - 15 + 16 - 17 = -2
5, 14 + 15 + 16 - 17 = 28
6, 14 - 15 - 16 + 17 = 0
7, 14 + 15 - 16 - 17 = -4
8, 14 - 15 + 16 + 17 = 32

The numbers are all even

Numbers 20, 21, 22, 23:

1, 20 + 21 + 22 + 23 = 86
2, 20 - 21 - 22 - 23 = -46
3, 20 + 21 - 22 + 23 = 42
4, 20 - 21 + 22 - 23 = -2
5, 20 + 21 + 22 - 23 = 40
6, 20 - 21 - 22 + 23 = 0
7, 20 + 21 - 22 - 23 = -4
8, 20 - 21 + 22 + 23 = 44

Compare the sets:

The numbers are all even in both sets. The sets of numbers both have 3 negative numbers and 5 other numbers - one of which is 0! Both of them include -2 in them.

Test

This is a test to see whether each pattern contains 3 negative numbers one 0, and 4 other numbers.

Numbers 54, 55, 56, 57:

1, 54 + 55 + 56 + 57 = 222
2, 54 - 55 - 56 - 57 = -144
3, 54 + 55 - 56 + 57 = 110
4, 54 - 55 + 56 - 57 = -2
5, 54 + 55 + 56 - 57 = 108
6, 54 - 55 - 56 + 57 = 0
7, 54 + 55 - 56 - 57 = -4
8, 54 - 55 + 56 + 57 = 112
Test complete.

New Rule - Consecutive Numbers backwards

Numbers 63, 62, 61, 60:

1, 63 + 62 + 61 + 60 = 246
2, 63 - 62 - 61 - 60 = 120
3, 63 + 62 - 61 + 60 = 124
4, 63 - 62 + 61 - 60 = 2
5, 63 + 62 + 61 - 60 = 126
6, 63 - 62 - 61 + 60 = 0
7, 63 + 62 - 61 - 60 = 4
8, 63 - 62 + 61 + 60 = 122

Here, there are no negative numbers - -4 became 4 and -2 became 2 !

Numbers 04, 03, 02, 01:

1, 4 + 3 + 2 + 1 = 10
2, 4 - 3 - 2 - 1 = -2
3, 4 + 3 - 2 + 1 = 6
4, 4 - 3 + 2 - 1 = 2
5, 4 + 3 + 2 - 1 = 8
6, 4 - 3 - 2 + 1 = 0
7, 4 + 3 - 2 - 1 = 4
8, 4 - 3 + 2 + 1 = 4

There is one negative number again -2, -4 has changed to two +4 [not a sum].

Comparing [with the other rule]: Answer 6 stays as 0. The negative numbers have become positive, [normal] numbers [i.e. -2 = 2 -4 = 4 ] This is because you take lower numbers, and add higher numbers.

 

Pupils from William Harding Combined School and also from Gorseland Primary School investigated these consecutive numbers as well. They tried many different sets of four consecutive numbers and all agreed with what Stuart (from William Harding) wrote:

I found out that there are 8 sums for every set of consecutive numbers 1 full add,1 full subtract, 3 with 2 adds and 3 with 2 subtracts.

The group from Gorseland also found three rules (if the numbers are in ascending order):