12.50 and 12.05 are different prices: read the decimal places together
By Erik Nilsen · Kroni2 min read
One small zero can change a money amount. When your child copies a price, check both the number before the decimal point and the places after it. This helps when several small amounts are added for a budget.
Give both prices two decimal places
In a hypothetical example, two optional items cost 12.50 and 7.05 units. These arbitrary figures are invented. We use decimal amounts on a worksheet without promising any particular payment method or cash-rounding rule.
12.50 means twelve units and fifty hundredths of a unit. 12.05 means twelve units and five hundredths. The difference is 0.45 units. However, 12.5 and 12.50 are the same number; the trailing zero adds no value.
Write the amounts beneath each other with decimal points aligned. 12.50 + 7.05 = 19.55. A practice budget of 20.00 leaves 20.00 − 19.55 = 0.45 units.
If your child mistakenly writes 12.05 on the first line, the sum becomes 19.10 and the calculated remainder is 0.90. They appear to have twice as much left, but the difference comes from one decimal place.
Check the number before adding
A practical snag is your child saying “twelve point five” while an adult records 12.05. Ask them to read the amount in hundredths when precision matters: “twelve and fifty hundredths”. Then look at the original price together.
You can also calculate in hundredths on paper: 1250 + 705 = 1955, then divide the answer by 100. Label the unit clearly so 1955 is not mistaken for whole money units.
This exercise concerns reading and recording accurately. Record an actual purchase using its confirmed final amount rather than assuming which decimal precision an app or payment service supports.
Ask your family: “Is the zero at the end, or before a digit where it changes the value?”
Carry the calculation into your family agreement
Kroni can keep track of your child's virtual balance. The app does not transfer money, so any actual purchase is paid for outside it. Agree on what you will record, then check the amount with your child afterwards. Do not deduct a possible cost as though the purchase had already happened. Read about allowance in Kroni.
