Bhagyashree Mukherje Yes

266+1 ≠ 267. As it is base=7 so the digits can't be >=7.

So 7 has to be written in base 7 form which is

i.e. 10. sum=0 and carry=1.

Again 6+1(carry) = 10 => sum=0 and carry=1

2+1=3 sum=3 carry=0

So, 266+1 = (300)_{7}

Shubham Aggarwal Do let me know if you can understand this