The correct option is
A 656
Number of labourers working initially
= 924
Number of labourers who fall sick
= 268
To find the number of labourers working after the sick labourers leave, we have to subtract 268 from 924.
Let us fill the numbers in the place value chart first.
We cannot subtract bigger numbers from smaller numbers.
So, we regroup 4 at ones places to 14 which makes 2 at tens place convert to 1.
Similarly, we regroup 1 at tens place to 11 by taking 1 from 9 at the hundreds place.
Finally, 9 is changed to 8 at hundreds place.
∴ The answer of 924 - 268 is 656.
Hence, 656 labourers are left to work on building the pillar.