Question 6
Beavers send digits on floating logs. A differently colored final log carries a check digit. To compute it, add digits in odd positions, multiply that sum by 3, then add the digits in even positions. The check digit is the units digit of the result. For example 8,4,2,5 gives (8+2)×3+(4+5)=39, so its check digit is 9.
In the next message the data are 4,1,an erased digit,7 and the final check digit is 8. Their order has not changed.
What remainder does the erased digit leave when divided by 4?
In the next message the data are 4,1,an erased digit,7 and the final check digit is 8. Their order has not changed.
What remainder does the erased digit leave when divided by 4?