Look at this shopping receipt. The total at the bottom says €38.95. You hand over two €20 notes. Roughly how much change should you get back? Would rounding the total to €40 be close enough to check the change is right, before you count every cent?

Watch four estimates worked one at a time: a sum, a division, a crowd of people and a multiplication. For each one, notice what gets rounded and to which place, then check the exact answer looks sensible next to the estimate.

Now we try the estimation jar. Before anyone counts, look at the jar of counters and estimate how many are inside. We'll gather a few estimates, then reveal the true count and see how close we got. Ask yourself: was your guess a sensible rough number, and how far off was it from the real total?

Today we work through three real Irish-context estimation tasks together, then a stretch. In your copy work each one: round to a sensible place, write the estimate, then find the exact answer and compare.

1. The school orders 1,180 copybooks to split evenly among 6 classes. Estimate first, then work out how many each class gets.
2. A concert sells 47,300 tickets across 4 nights. Estimate the tickets per night, then find the exact figure.
3. A farmer harvests 2,985 kg of potatoes over 5 days. Estimate the daily harvest, then calculate it exactly.
4. Stretch: Which of your three estimates would you trust enough to plan with, and why?