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Ethiopian multiplication: Difference between revisions
C
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:[http://www.ncetm.org.uk/blogs/3064 Ethiopian multiplication]
:[http://www.bbc.co.uk/dna/h2g2/A22808126 Russian Peasant Multiplication]
=={{header|C}}==
<lang c>#include <stdio.h>
#include <stdbool.h>
void halve(int *x) { *x >>= 1; }
void doublit(int *x) { *x <<= 1; }
bool iseven(const int x) { return (x%2) == 0; }
int ethiopian(int plier,
int plicand, const bool tutor)
{
int result=0;
if (tutor)
printf("ethiopian multiplication of %d by %d\n", plier, plicand);
while(plier >= 1) {
if ( iseven(plier) ) {
if (tutor) printf("%4d %6d struck\n", plier, plicand);
} else {
if (tutor) printf("%4d %6d kept\n", plier, plicand);
result += plicand;
}
halve(&plier); doublit(&plicand);
}
return result;
}
int main()
{
printf("%d\n", ethiopian(17, 34, true));
return 0;
}</lang>
=={{header|Python}}==
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