Help with a number sequence! Year 4, but really hard [blush]

6 replies

Sticklebug · 07/05/2013 20:43

My year 4 DD has been asked to complete the following number sequence.

7, 19, 55

She has no idea, my older DD has no idea and I have absolutely no idea.....Any help???

OP posts:

AnythingNotEverything · 07/05/2013 20:50

Is it times by 3 and minus 2?

SconeInSixtySeconds · 07/05/2013 20:51

7x3 = 21
21-2 = 19

19x3=57
57-2=55

It's a two step pattern..evil but fun to us mad maths sickos

Original poster

Sticklebug · 07/05/2013 20:51

My DD(11) has just rushed down stairs saying the same thing....I just could not see it!

OP posts:

Original poster

Sticklebug · 07/05/2013 20:52

Is this hard for yr4...or maybe I am not as good at maths as i thought!

OP posts:

richmal · 08/05/2013 11:08

There are some good expanations for the sequence 3, 7, 19, 55 on nrich.

mccandjt · 20/05/2013 14:38

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