A series trying to give butterflies

Number Theory Level 3

Consider the series 1,1,2,3,5,8,13,21,..... What is the unit digit of the sum of 88th and 89th term of this series?


The answer is 0.

Sahil Gupta by Sahil Gupta , 28, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Arijit Banerjee
Mar 30, 2014

88th number is 1100087778366101931 89th number is 1779979416004714189 hence unit digit of sum of these two is 0

1 Helpful 0 Interesting 0 Brilliant 0 Confused

It is a really very lengthy computational problem, yet fun!

Krishna Ar - 7 years, 2 months ago

how did you computed these lengthy digits

Parth Lohomi - 6 years, 11 months ago

M.hareesh method is good.60 is the cycle.

nagarjuna reddy - 5 years, 8 months ago

simple.just add the unit digits and after 60th term it repeats unit digit from starting ,so that 88th term unit digit is 1 and 89th unit digit is 9 ..indirectly asking unit digit of 90th term

0 Helpful 0 Interesting 0 Brilliant 0 Confused

I do it the same method

Gonna Sing - 6 years, 10 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...