JUST A MODULO PROBLEM!!

A number X when divided by 10 gives 9 as remainder, when divided by 9 gives 8 and so on to..... when divided by 2 gives 1 as remainder. Find this least value of X?


The answer is 2519.

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3 solutions

Jaiveer Shekhawat
Sep 17, 2014

since, we have to find x,

we will proceed by using Remainder theorem or the Modulo method!

given,

x=9(mod10)

x=8(mod9)

x=7(mod8)

x=6(mod7)

x=5(mod6)

x=4(mod5)

x=3(mod4)

x=2(mod3)

x=1(mod2)

thus, adding 1 on both sides we get,

x+1=0(mod10)

x+1=0(mod9)

x+1=0(mod8)

x+1=0(mod7)

x+1=0(mod6)

x+1=0(mod5)

x+1=0(mod4)

x+1=0(mod3)

x+1=0(mod2)

thus, (x+1) is divisible by 10,9,8.....2.

thus, it the L.C.M. of 10,9,8.....2.

=(10)x(9)x(4)x(7)

=2520 thus, the answer is x, one less than 2520

=2519

sir what is MOD?

Ecky Wecky - 6 years, 8 months ago

Log in to reply

a mod b implies the remainder when a is divided by b

Vighnesh Raut - 6 years, 8 months ago

It is used in modular arithmetic

Manish Mayank - 6 years, 8 months ago
David Holcer
Apr 18, 2015

Nice solutions, I went for the code :)

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c=0
while True:
    works=True
    a=9
    while a>2 and works:
        if c%a==a-1:
            works=True
        else:
            works=False
        a-=1
    if works:
        print c
        break
    c+=1

Aareyan Manzoor
Oct 9, 2014

lcm of the integers -1

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