$(11+11) \times(12+12)\times (13+13)...\times(18+18)\times(19+19)=x$

What is the remainder ,if $x$ is divided by $10$?

## BdMO National Primary 2016/2

### Re: BdMO National Primary 2016/2

$(11+11) \times (12+12) \times (13+13) \times...\times (18+18) \times (19+19)=22 \times 24 \times 26 \times...\times 38$

Here, the

As $x=30 \times y$

So, $10|x$

Remainder=$0$

Here, the

**fifth**term will be: $(15+15)=30$ which is divisible by $10$As $x=30 \times y$

So, $10|x$

Remainder=$0$

**[Can't simplify more for primary ]**- samiul_samin
**Posts:**1007**Joined:**Sat Dec 09, 2017 1:32 pm

### Re: BdMO National Primary 2016/2

I was thinking about how to solve it simply.It is much more simple than my solution.Tasnood wrote: ↑Thu Feb 15, 2018 4:16 pm$(11+11) \times (12+12) \times (13+13) \times...\times (18+18) \times (19+19)=22 \times 24 \times 26 \times...\times 38$

Here, thefifthterm will be: $(15+15)=30$ which is divisible by $10$

As $x=30 \times y$

So, $10|x$

Remainder=$0$

[Can't simplify more for primary ]