To increase £258 by 43%, we can use the multiplier method.
First, we need to calculate the multiplier. The multiplier is 1 plus the percentage increase as a decimal. In this case, the percentage increase is 43%, which is 0.43 as a decimal. So the multiplier is:
Multiplier = 1 + 0.43 = 1.43
Next, we can use the multiplier to find the new amount after the increase. We do this by multiplying the original amount by the multiplier. In this case, we want to increase £258, so the new amount is:
New amount = £258 x 1.43 = £368.94 (rounded to the nearest penny)
Therefore, the new amount after increasing £258 by 43% using the multiplier method is £368.94.