Some types of mental calculation require specialist methods to solve them. Here are some popular ones with worked examples:
- Human Calendar Method — learn the algorithm used by experts
- Cross-Multiplication — multiply huge numbers at exceptional speed
- Cross-Division — divide by long numbers such as 4.52188
- Fraction Addition and Subtraction — with advice on when and how simplify answers
- Fraction Multiplication and Division — including conversion between mixed and improper form
- Square Roots:
- Fast Method to Estimate Square Roots — to 3–5 decimal places
- Method for Exact Square Roots — where you know the answer will be an integer
- Accurate Method for Square Roots — to unlimited decimal places (2-digit division method)
- Deep Roots:
- Fast Method to Estimate Deep Roots — to 2–3 decimal places
- Method for Exact Cube Roots — where you know the answer will be an integer
- Accurate Method for Cube Roots — to unlimited decimal places
- Difficult Roots and Difficult Powers — logarithm method
- Logarithms and Antilogarithms — product-building method
- Hectoc strategies
