Flash questions
Short drills on core skills, drawn at random each time you open one. A wall of cards to project, print or run as a timed slideshow — answers stay hidden until you ask for them.
All series shuffled togetherA wall drawn from the whole catalogue: each card comes from a different series, with no warning.Open the shuffle Mental maths challengeAs many maths questions as you can in 1 or 5 minutes, against the clock.Start the challengeTimes tables
The 2 to 12 times tables, both ways round: the product asked for, or the missing factor.
Order of operations
Chaining additions, multiplications and brackets in the right order, without falling for how the calculation is written.
Decimal form of simple fractions
Going from a simple fraction to its decimal form and back to the fraction, in your head, without long division.
Fractions in lowest terms
Reducing a fraction to its lowest terms by spotting the common divisor at a single glance.
Sums of fractions
Adding or subtracting two fractions and giving the result in its lowest terms.
Percentages of a number
Taking a simple percentage of a number, and recognising an increase or a decrease.
Arithmetic with signed numbers
Adding, subtracting and multiplying signed numbers, where the signs trip up the reflexes.
Squares and square roots
Squares up to 30, exact square roots, and bracketing the roots that do not come out whole.
GCD and LCM
Finding the greatest common divisor and the least common multiple of two whole numbers, without writing out the factorisation.
Powers of ten and scientific notation
Moving between scientific notation and decimal form, and back, without a calculator.
Unit conversions
Lengths, masses, capacities and durations: changing units without a conversion table.
Pythagorean theorem
Finding the hypotenuse, the missing side or the perimeter of a right triangle, on the integer triples that come out exactly.
Areas and perimeters
Working out the area or the perimeter of the usual shapes — square, rectangle, triangle, disc — without opening the formula sheet.
Mean and median
Reading a short list of numbers and giving its mean, median or range without writing anything down.
Linear equations
Solving an equation of the form ax + b = c in your head, with a whole-number solution.
Special products
Expanding (a + b)², (a − b)² and (a + b)(a − b), coefficient in front of x included, and recognising them in order to factorise.
Rules of exponents
Multiplying, dividing and raising powers, with or without a coefficient in front: the exponent rules that must become automatic.
Discriminant and roots
Discriminant, sum and product of the roots of a quadratic, read straight off the coefficients.
Special values on the unit circle
Cosines, sines and tangents of the notable angles of the full circle, in radians as well as in degrees.
Logarithm and exponential
The reference values of ln and exp, along with the product, quotient and power rules.
Standard limits
The reference limits, the highest-degree term of polynomials and quotients, and comparative growth.
Standard derivatives
Differentiating from memory: reference functions, powers of x, polynomials and simple compositions.
Standard antiderivatives
Working back to antiderivatives up to a constant: reference functions, powers, polynomials and simple compositions.
Term of a sequence
Working out a term of an arithmetic or geometric sequence from its first term and its common difference or ratio.
Complex numbers
Powers of i, modulus and conjugate: the reflexes that save time on any complex-number calculation.
What are flash questions for?
A flash question is answered in seconds, in your head. Strung into a short series, they keep sharp the basics — times tables, fractions, conversions, formulas — that longer exercises already assume. Every wall is drawn afresh: the same series never comes back identical, unless you keep its address.