Question

Find the cube root of the number 1,03,823
by unit digits method.
47​

Answer 1

Here the units digit of 103823 is 3.

if n³= 103823

then the units digit of n must be 7

Let us split 103823 as 103 and 823.

We observe that 4³

=64< 103 < 125= 5³

Hence,

40³=64000<103823<125000=50³

Hence n must lie between 40 and 50. Since the units digit of n is 7, the only such number is 47. You may check that

47³= 103823