Thanks for reply, I used this constructor for reduce memory size :
U8G2_SH1106_128X64_NONAME_1_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE)
and choose font with "tr" and just a number "tn" for draw display result.
And so create some global function and variable to reduce memory size/sketch.