How many ohm's is a 1M5 resistor?

The plural of 'ohm' is ohms, not ohm's.

The alpha-numeric code for identifying the resistance of a resistor is quite straightforward.

The letter is used as a multiplier. For example, k= x1000 and M = x1000 000. In other Words, k represents kilo, and M represents mega.

The position of the letter represents the position of the decimal marker.

So,

• 1M5 represents 1.5 x 1000 000, or 1.5 megohms.
• 15M represents 15 x 1000 000, or 15 megohms.
• etc.

Similarly,

• 1k5 represents 1.5 x 1000, or 1.5 kilohms.
• 15k represents 15 x 1000, or 15 kilohms.
• etc.