A maths worksheet intended for a 10-year-old prompted a flurry of online explanations after a UK parent posted their long division workings to a Reddit homework-help thread and asked why their answer appeared incorrect.
The parent shared an image of the child's Year 6 (Grade 5) assignment showing the problem 861 divided by 4 and their calculated result of 215.1. Commenters on the forum pointed out the correct answer is 215.25 and explained the error stemmed from how the remaining 1 was handled when converting a remainder into a decimal.
Several respondents walked through the conventional long division process to show where the poster went wrong. After dividing 861 by 4, the student arrives at a remainder of 1; that remainder should not be written as 0.1. Instead, the remainder is expressed as 1/4, which equals 0.25. One commenter wrote that the parent had been "doing great up until you got a remainder of 1," and advised converting the remainder by appending a zero to the dividend (making it 861.00) and continuing the division so the decimal places align correctly.
Others offered simple arithmetic reminders: placing the leftover 1 over the divisor (1/4) yields 0.25, not 0.1. Several users recommended practical tips for performing and presenting long division, including writing each step on its own line and ensuring the decimal point in the quotient is positioned above the decimal in the dividend.
The post referenced a common classroom mnemonic used to teach long division steps — "Do Monkeys Smell Bad" — representing divide, multiply, subtract and bring down. Commenters used that framework to trace the calculation and show how to continue the algorithm once the whole-number part of the quotient is complete and a remainder remains.
Reactions on the thread mixed instruction with mild criticism. One commenter urged the original poster to try again and to treat the dividend as 861.00 so that adding decimal places in the answer is clear. Another dismissed the struggle, writing that it was "sad to see adults stymied by very simple math." Several responses aimed to be constructive, offering both the arithmetic correction and organizational advice for future long division problems.
Long division remains a standard element of primary-school maths curricula in the UK and elsewhere, and teachers typically require students to show full working to demonstrate understanding. The exchange highlights a recurring source of confusion for learners and adults alike: converting remainders into decimal fractions and aligning decimal points when continuing the division into tenths and hundredths. The parent’s post is one of several recent social-media threads in which routine school exercises have sparked broader discussion among adults seeking to help children with homework.