Alternatives for finding n significant figures

Note

The following formula calculates N significant figures
- ROUND( your cell , precision -(1+INT(LOG10(ABS( your cell )))))
- CITE: https://exceljet.net/formula/round-a-number-to-n-significant-digits

values	results	comments

values	results	comments
123456789		TEXT(IF(A1<0,"-","")&LEFT(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00"),3+1)10^FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1),(""&(IF(OR(AND(FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1)+1=3,RIGHT(LEFT(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00"),3+1)10^FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1),1)="0"),LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00"))<=3-1),"0.","#")&REPT("0",IF(3-1-(FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1))>0,3-1-(FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1)),0))))) don’t work under investigation
123456789		ROUND(a2,3-(1+INT(LOG10(ABS(a2)))))
123800210		ROUND(a3,3-(1+INT(LOG10(ABS(a3)))))
13.123		ROUND(a4,3-(1+INT(LOG10(ABS(a4))))) with a format, “#.#”
13		ROUND(a5,3-(1+INT(LOG10(ABS(a5))))) with a format, “#.#”

table2

values	results	comments

values

results

comments

123456789

TEXT(IF(A1<0,"-","")&LEFT(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00"),3+1)*10^FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1),(""&(IF(OR(AND(FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1)+1=3,
RIGHT(TEXT(LEFT(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00"),3+1)*10^FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1), "#."),1)
="0"),LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00"))<=3-1),"0.","#")&REPT("0",IF(3-1-(FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1))>0,3-1-(FLOOR(LOG10(TEXT(ABS(A1),"0."&REPT("0",3-1)&"E+00")),1)),0)))))

First argument of RIGHT function must be String.

So, inserted TEXT(val, “#”) after RIGHT function.