Not far into the future, mortality rates are very low and so the assessment of household needs (the survival probabilities multiplied by the relevant equivalence scales) are close to the equivalence scale values. Thus, when both children are under 18, the value is close to 2 (the square root of 4) and with just one child, 1.73 (the square root of 3). When both children are 18, the curve drops to 1.34, a little below the equivalence scale of 1.41, because the probability of one partner dying before this point is no longer negligible. The curves then diminish slowly to zero.