Problem
NT-B1-M10-P001 Remainder by Digit Sum
#1
★☆☆☆☆ Level 1 of 5
Find the remainder of \(7345821\) when divided by \(9\), without long division.
Use \(10\equiv1\pmod9\).
The digit sum is \(7+3+4+5+8+2+1=30\). Since \(30\equiv3\pmod9\), the original number also has remainder \(3\).
Basic check that the student understands the rule as a congruence.