A piece of cake. 씩 is a piece of something. like saying "a piece" "per" or "만큼" and is used with money a lot.
우리 아이에게 만원씩 줬어
I gave each of my kids ten dollars.
I gave my kids ten dollars a piece.
조금씩 먹어라
eat nice and slow; chew your food (piece by piece)
보통 하루에 네 번씩 식사를 해요
I usually eat four times a day.
저는 날마다 10시간씩 근무해요
I work 10 hours a day.
한 학생에 사탕 두 새씩 줬어요
I gave two pieces of candy to each student.
한 주 다섯 번씩 운동해요
I work out five times a week.
가끔씩
sometimes
식 (式) is much more versatile and is used much more frequently. The form that was getting me confused with the spelling was the ~식 that stands for "ceremony" or "way"
결혼식
wedding ceremony
미국식으로
American way
졸업식
graduation ceremony
장례식
funeral
성찬식
communion
이런식으로...
this way
