It's only a dead cat - no need to worry. The whole thing will be quietly forgotten once it's served to distract everyone from the Prime Minister's current problems.
However... just in case anyone's actually serious about this, here's a selection of questions from "Intelligence Arithmetic Tests", Pupils' Book II for Intermediate Classes aged 10 to 12 Years, published by Schofield & Sims some time during the 1950s - because these offer a flavour of what your kids might need to be able to cope with.
I've omitted several questions that would require familiarity with pre-decimal currency (£.s.d.), but left in a few that only need a simple calculation using old pence. The kids would have been expected to answer all twenty questions in a single period of about 50 minutes. Here we go...
A milkman buys his milk at 10d. per gall. and sells it at 4d. per quart. How much does he gain on 5 galls.?
A person sold 2 eggs each day during June. If they were 1½d. each, how much was obtained for them?
If the value of a square chain of land is £5, what should be paid for an acre?
A piece of cloth 3 yds. 2 inches long is cut into 11 equal strips. How long is each strip?
If ¾ cwt. of tea be made up into quarter pound packets, how many would there be?
Find the price of 3 lbs. of tea at 1½d. per oz.
How many inches are left after ¾ of a yard measure has been cut off?
If milk costs 4d. per quart, what will 2½ galls. cost?
What is the difference between 9 doz. and 9 score?
If a milkman leaves ½ pint of milk at each of 24 houses, how many galls. is that?
A piece of string is 1 ft. 3 in. long. How many such pieces would be required to stretch 3 yds. 1 ft.?
If 1½ lbs. of sweets were divided among 4 boys, how much would each receive?
If a gallon of water weighs 10 lbs., what will 1 gall. 3 pts. weigh?
If 7 lbs. of soap be cut into 4 oz. tablets, how many will there be?
What does 1 lb. of wool at 4½d. per oz. cost?
How many lb. packets of tea can be made from 1½ cwts?
A man had ¾ of an acre to plough. He did one eighth of an acre on the first day, and a quarter of an acre on the second day. How much remained to be done?
A rail is 3 ft. 9 in. long, and 26 of them are placed end to end. How far will they stretch? Answer in inches.
A plant has grown from 2 ft. 3 ins. to 5 ft. 2 ins. in one season. What is the increase in height?
What would a gross of matches cost at 10½d. per doz.?
[Sooooo... how did you get on? Nothing to worry about then :) ]