#DIV/0! appears when a number is divided by zero or by a blank cell (treated as zero). Common in ratios and averages over empty data.
Guard with IF
Use =IF(B2=0, "", A2/B2) to skip zero divisors.
Use IFERROR
Wrap with =IFERROR(A2/B2, 0) to show 0 instead.
Use =IFERROR(A2/B2, "") so empty/zero divisors return a blank.