Arbitrary addition, subtraction and multiplication without arithmetic signs.

int add( int a, int b ) { while ( a ) { int c = a & b; b ^= a; a = c << 1; } return b; }

int sub( int a, int b ) { return add( a, add( ~b, 1 ) ); }

int mul( int a, int b ) { int c = 0; while ( a ) { if ( a & 1 ) c = add( c, b ); a >>= 1; b <<= 1; } return c; }