31.61kg=31.6kg to 1dp
2.25kg=2.3kg to 1dp
23.29g=23.3g to 1dp
1dp just means that there needs to be 1 number after the . and you choose which number by looking at the second number after the point, if it is 5 or more, the first number after the point is increased by one, if it is less than 5 the first number stays the same.