Originally Posted by

**MissTK** "Look at the question to see how many decimal places are needed for x and keep going until you have an answer that is more accurate and then round off. For this example, the answer needs to be to 2dp, so we need one more decimal place to know whether to round up or down."

Is this what you were having trouble with? What you need to know in order to decide when to stop, is how accurate you want the answer to be.

In this case, you need the answer to be accurate to two decimal places. You keep going until you can be completely sure about the first two decimal places.. Before you did the last try, you knew that 1.72 was too big and 1.71 too small, so you know the answer is between those, but you don't know if you should round up or down. When you've tried 1.714 and that's too big, you have narrowed it down to between 1.71 and 1.714. These are both 1.71 when you use two decimal places, so you know the answer has to be 1.71.

In the Maths Online example, there was nothing in the problem about how accurate it needed to be, so it's actually a bit unclear. I think the explanation in the end is bad, though. You should probably keep going at least until you have one answer over and one under.

7 + 3 = 10, 7 x 3 = 21 too big

8 + 2 = 10, 8 x 2 = 16 too small

7.5 + 2.5 = 10, 7.5 x 2.5 = 18.75 too small

7.3 + 2.7 = 10, 7.3 x 2.7 = 19.71 too small, but pretty close.. not close enough ? !

7.2 + 2.8=10, 7.2 * 2.8= 20.16 (that's closer, so the previous one wasn't correct)

If you try 7.24*2.76 you go under again, so I think I would give the answer to two decimal places as 7.2 and 2.8.