diff --git a/engine/battle/ai/items.asm b/engine/battle/ai/items.asm
index 4d1eea2e8..060c53ad6 100644
--- a/engine/battle/ai/items.asm
+++ b/engine/battle/ai/items.asm
@@ -52,7 +52,7 @@ SwitchOften: ; 38045
 	cp $10
 	jr nz, .not_10
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jr c, .switch
 	jp DontSwitch
 .not_10
@@ -60,7 +60,7 @@ SwitchOften: ; 38045
 	cp $20
 	jr nz, .not_20
 	call Random
-	cp -1 + 79 percent
+	cp 79 percent - 1
 	jr c, .switch
 	jp DontSwitch
 .not_20
@@ -103,7 +103,7 @@ SwitchRarely: ; 38083
 
 	; $30
 	call Random
-	cp -1 + 79 percent
+	cp 79 percent - 1
 	jp c, DontSwitch
 
 .switch
@@ -123,7 +123,7 @@ SwitchSometimes: ; 380c1
 	cp $10
 	jr nz, .not_10
 	call Random
-	cp -1 + 20 percent
+	cp 20 percent - 1
 	jr c, .switch
 	jp DontSwitch
 .not_10
@@ -131,14 +131,14 @@ SwitchSometimes: ; 380c1
 	cp $20
 	jr nz, .not_20
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jr c, .switch
 	jp DontSwitch
 .not_20
 
 	; $30
 	call Random
-	cp -1 + 20 percent
+	cp 20 percent - 1
 	jp c, DontSwitch
 
 .switch
@@ -313,7 +313,7 @@ AI_Items: ; 39196
 	bit ALWAYS_USE_F, a
 	jp nz, .Use
 	call Random
-	cp -1 + 20 percent
+	cp 20 percent - 1
 	jp c, .Use
 	jp .DontUse
 
@@ -325,7 +325,7 @@ AI_Items: ; 39196
 	cp 4
 	jr c, .FailToxicCheck
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jp c, .Use
 .FailToxicCheck:
 	ld a, [wEnemyMonStatus]
@@ -366,7 +366,7 @@ AI_Items: ; 39196
 	callfar AICheckEnemyQuarterHP
 	jp nc, .UseHealItem
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jp c, .UseHealItem
 	jp .DontUse
 
@@ -374,7 +374,7 @@ AI_Items: ; 39196
 	callfar AICheckEnemyQuarterHP
 	jp c, .DontUse
 	call Random
-	cp -1 + 20 percent
+	cp 20 percent - 1
 	jp c, .DontUse
 	jr .UseHealItem
 
@@ -384,7 +384,7 @@ AI_Items: ; 39196
 	callfar AICheckEnemyQuarterHP
 	jp nc, .UseHealItem
 	call Random
-	cp -1 + 20 percent
+	cp 20 percent - 1
 	jp nc, .DontUse
 
 .UseHealItem: ; 38281 (e:4281)
@@ -442,7 +442,7 @@ AI_Items: ; 39196
 	bit UNKNOWN_USE_F, a
 	jp z, .Use
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jp c, .Use
 
 .dont_use
@@ -454,7 +454,7 @@ AI_Items: ; 39196
 	bit UNKNOWN_USE_F, a
 	jp z, .DontUse
 	call Random
-	cp 1 + 39 percent
+	cp 39 percent + 1
 	jp c, .Use
 	jp .DontUse
 ; 382f9
@@ -516,13 +516,13 @@ AI_Items: ; 39196
 	bit ALWAYS_USE_F, a
 	jp nz, .Use
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jp c, .DontUse
 	ld a, [bc]
 	bit CONTEXT_USE_F, a
 	jp nz, .Use
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jp c, .DontUse
 	jp .Use
 .notfirstturnout
@@ -530,7 +530,7 @@ AI_Items: ; 39196
 	bit ALWAYS_USE_F, a
 	jp z, .DontUse
 	call Random
-	cp -1 + 20 percent
+	cp 20 percent - 1
 	jp nc, .DontUse
 	jp .Use
 
diff --git a/engine/battle/core.asm b/engine/battle/core.asm
index 419129e10..a1ccc0340 100644
--- a/engine/battle/core.asm
+++ b/engine/battle/core.asm
@@ -463,13 +463,13 @@ DetermineMoveOrder: ; 3c314
 	jr z, .player_2
 
 	call BattleRandom
-	cp 1 + (50 percent)
+	cp 50 percent + 1
 	jp c, .player_first
 	jp .enemy_first
 
 .player_2
 	call BattleRandom
-	cp 1 + (50 percent)
+	cp 50 percent + 1
 	jp c, .enemy_first
 	jp .player_first
 
@@ -549,13 +549,13 @@ DetermineMoveOrder: ; 3c314
 	cp USING_INTERNAL_CLOCK
 	jr z, .player_2c
 	call BattleRandom
-	cp 1 + (50 percent)
+	cp 50 percent + 1
 	jp c, .player_first
 	jp .enemy_first
 
 .player_2c
 	call BattleRandom
-	cp 1 + (50 percent)
+	cp 50 percent + 1
 	jp c, .enemy_first
 .player_first
 	scf
@@ -791,7 +791,7 @@ TryEnemyFlee: ; 3c543
 
 	call BattleRandom
 	ld b, a
-	cp 1 + (50 percent)
+	cp 50 percent + 1
 	jr nc, .Stay
 
 	push bc
@@ -803,7 +803,7 @@ TryEnemyFlee: ; 3c543
 	jr c, .Flee
 
 	ld a, b
-	cp 1 + (10 percent)
+	cp 10 percent + 1
 	jr nc, .Stay
 
 	ld a, [wTempEnemyMonSpecies]
@@ -6177,7 +6177,7 @@ LoadEnemyMon: ; 3e8eb
 
 ; 25% chance of getting an item
 	call BattleRandom
-	cp 1 + (75 percent)
+	cp 75 percent + 1
 	ld a, NO_ITEM
 	jr c, .UpdateItem
 
diff --git a/engine/battle/effect_commands.asm b/engine/battle/effect_commands.asm
index 5a0c130bd..376624e44 100644
--- a/engine/battle/effect_commands.asm
+++ b/engine/battle/effect_commands.asm
@@ -532,7 +532,7 @@ CheckEnemyTurn: ; 3421f
 
 	; 50% chance of hitting itself
 	call BattleRandom
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jr nc, .not_confused
 
 	; clear confusion-dependent substatus
@@ -578,7 +578,7 @@ CheckEnemyTurn: ; 3421f
 
 	; 50% chance of infatuation
 	call BattleRandom
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	jr c, .not_infatuated
 
 	ld hl, InfatuationText
diff --git a/engine/events/daycare.asm b/engine/events/daycare.asm
index 7da559e75..ddfa5b89c 100755
--- a/engine/events/daycare.asm
+++ b/engine/events/daycare.asm
@@ -665,7 +665,7 @@ DayCare_InitBreeding: ; 16a3b
 	cp NIDORAN_F
 	jr nz, .GotEggSpecies
 	call Random
-	cp 1 + 50 percent
+	cp 50 percent + 1
 	ld a, NIDORAN_F
 	jr c, .GotEggSpecies
 	ld a, NIDORAN_M