perussummaus

Perussummaus is a Finnish term referring to the basic act of summing numbers to obtain a total. In Finnish mathematics education, it denotes the fundamental operation of addition, encompassing both mental calculation and written algorithms for adding two or more addends. The word combines perus (basic, fundamental) with summaus (summation). It is used to distinguish simple addition from more advanced or specialized summation concepts.

In classroom practice, perussummaus is taught as the starting point for arithmetic fluency. Students learn the commutative and associative properties of addition, understand regrouping (carrying) when sums exceed ten, and practice decomposing numbers into tens and ones to simplify calculation. Early work focuses on small numbers and oral or written sums, with gradual progression to larger numbers and multi-term additions. The goal is to develop accuracy, speed, and number sense through repeated, varied exercises.

Examples of perussummaus include basic sums such as 7 + 8 = 15, and more complex cases like 34 + 29 = 63 or 56 + 47 + 12 = 115. In higher grades, the concept extends to multi-step additions and the use of estimation to check results, while still centering on the fundamental skill of combining quantities to form a total.

See also: addition, arithmetic, mental math, number sense.