Questions about reducing

[Mooglebass]

How would i go about reducing a batch? Would i just half the ingredients? Is there more to it than that? I was planing on doing BMs centennial blonde extract version. It lists this for a 5 gallon batch.
Ingredients:
------------
Amount Item Type % or IBU
5.00 lb Extra Light Dry Extract (3.0 SRM) Dry Extract 83.3 %
1.00 lb Cara-Pils/Dextrine (2.0 SRM) Grain 16.7 %
0.25 oz Centennial [9.50%] (45 min) Hops 7.8 IBU
0.25 oz Centennial [9.50%] (20 min) Hops 5.1 IBU
0.25 oz Cascade [7.80%] (10 min) Hops 2.5 IBU
0.25 oz Cascade [7.80%] (5 min) Hops 1.4 IBU
1 Pkgs Nottingham (Danstar #-) Yeast-Ale
__________________

if i was to make a 2.5 gallon batch would it look like this?

Ingredients:
------------
Amount Item Type % or IBU
2.5 lb Extra Light Dry Extract (3.0 SRM) Dry Extract 83.3 %
.50 lb Cara-Pils/Dextrine (2.0 SRM) Grain 16.7 %
0.125 oz Centennial [9.50%] (45 min) Hops 7.8 IBU
0.125 oz Centennial [9.50%] (20 min) Hops 5.1 IBU
0.125 oz Cascade [7.80%] (10 min) Hops 2.5 IBU
0.125 oz Cascade [7.80%] (5 min) Hops 1.4 IBU
1 Pkgs Nottingham (Danstar #-) Yeast-Ale

Or is there a better formula to do it with? Id really like to do more like a 4 gallon batch of brew as that is what i can do for now. Just i am not sure how to go about reducing the recipes

 

[DocScott]

Yes. Multiply all ingredients by whatever scaled ratio you choose.

 

[Calder]

Looks fine.

As you rightly assumed, it is not worth halving the yeast. Once opened it can get contaminated. But if you are planning a lot of small batches, you can reseal the packet if you are careful.