Verbseoul.
하다 verb
가감하다gagamhadato add and reduce

To say to add and reduce politely in the present tense, use 가감해요 (gah-gahm-hae-yoh). Below is the full conjugation of 가감하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
가감해
gah-gahm-hae
가감해요
gah-gahm-hae-yoh
가감합니다
gah-gahm-hahm-nee-dah
Past
가감했어
gah-gahm-hae-ssuh
가감했어요
gah-gahm-hae-ssuh-yoh
가감했습니다
gah-gahm-hae-sseum-nee-dah
Future
가감할 거야
gah-gahm-hahl- -guh-yah
가감할 거예요
gah-gahm-hahl- -guh-yae-yoh
가감할 겁니다
gah-gahm-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
가감하세요
gah-gahm-hah-sae-yoh
Suggestion / Let's Polite (요)
가감해요
gah-gahm-hae-yoh
Question Polite (요)
가감해요?
gah-gahm-hae-yoh-?
Connective “and” — (고)
가감하고
gah-gahm-hah-goh
Conditional “if” — (면)
가감하면
gah-gahm-hah-myuhn
Noun form — (기)
가감함
gah-gahm-hahm