@socks yeah it's often really hard to tell apart blue and purple on a metal film resistor, or orange and red and brown on a carbon-composition resistor, because of the dyes they use in conjunction with the resistor's body color

we often have to fall back on our knowledge of what the E12 series values are and that's not really a good thing
-F

@socks (E12 values are the preferred values for 10% resistors and the most common ones available for 5% and 1% ones too, they're

1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2

of those, the most common ones are the E6 values,

1.0, 1.5, 2.2, 3.3, 4.7, 6.8

which are nominally for 20% tolerance devices

oops now i'm rambling
-F)

@socks the general idea is that if you take all the E12 numbers ±10%, that covers an entire decade of values. same goes for the E6 numbers ±20%, and for tighter tolerances there's also E24 and E48 all the way down to E192 for 0.5%
-F

@socks E12 actually doesn't quite cover the whole decade since they're rounded to two digits, there's a little gap between 1.2+10% (1.32) and 1.5-10% (1.35)
-F