diff --git a/Mathlib/Algebra/Quaternion.lean b/Mathlib/Algebra/Quaternion.lean
index 45ac70fdc75648..ddf0adc010ee10 100644
--- a/Mathlib/Algebra/Quaternion.lean
+++ b/Mathlib/Algebra/Quaternion.lean
@@ -1173,6 +1173,18 @@ instance instRatCast : RatCast ℍ[R] where ratCast q := (q : R)
 
 @[norm_cast] lemma coe_ratCast (q : ℚ) : ↑(q : R) = (q : ℍ[R]) := rfl
 
+section ofScientific
+open OfScientific (ofScientific)
+variable (m : ℕ) (s : Bool) (e : ℕ)
+
+@[norm_cast] lemma coe_ofScientific : ((ofScientific m s e : R) : ℍ[R]) = ofScientific m s e := rfl
+@[simp] lemma re_ofScientific : (ofScientific m s e : ℍ[R]).re = ofScientific m s e := rfl
+@[simp] lemma imI_ofScientific : (ofScientific m s e : ℍ[R]).imI = 0 := rfl
+@[simp] lemma imJ_ofScientific : (ofScientific m s e : ℍ[R]).imJ = 0 := rfl
+@[simp] lemma imK_ofScientific : (ofScientific m s e : ℍ[R]).imK = 0 := rfl
+
+end ofScientific
+
 variable [LinearOrder R] [IsStrictOrderedRing R] (a b : ℍ[R])
 
 @[simps -isSimp]
diff --git a/Mathlib/Analysis/RCLike/Basic.lean b/Mathlib/Analysis/RCLike/Basic.lean
index 399b516ef12d46..61526831694472 100644
--- a/Mathlib/Analysis/RCLike/Basic.lean
+++ b/Mathlib/Analysis/RCLike/Basic.lean
@@ -631,6 +631,20 @@ theorem ratCast_re (q : ℚ) : re (q : K) = q := by rw [← ofReal_ratCast, ofRe
 @[simp, rclike_simps, norm_cast]
 theorem ratCast_im (q : ℚ) : im (q : K) = 0 := by rw [← ofReal_ratCast, ofReal_im]
 
+open OfScientific (ofScientific)
+
+@[rclike_simps, norm_cast]
+theorem ofReal_ofScientific (m : ℕ) (s : Bool) (e : ℕ) :
+    ((ofScientific m s e : ℝ) : K) = ofScientific m s e := ofReal_nnratCast _
+
+@[simp, rclike_simps]
+theorem ofScientific_re (m : ℕ) (s : Bool) (e : ℕ) :
+    re (ofScientific m s e : K) = ofScientific m s e := by rw [← ofReal_ofScientific, ofReal_re]
+
+@[simp, rclike_simps, norm_cast]
+theorem ofScientific_im (m : ℕ) (s : Bool) (e : ℕ) :
+    im (ofScientific m s e : K) = 0 := by rw [← ofReal_ofScientific, ofReal_im]
+
 /-! ### Norm -/
 
 theorem norm_of_nonneg {r : ℝ} (h : 0 ≤ r) : ‖(r : K)‖ = r :=
diff --git a/Mathlib/Data/Complex/Basic.lean b/Mathlib/Data/Complex/Basic.lean
index 969f69b3353927..36982101ed7b6e 100644
--- a/Mathlib/Data/Complex/Basic.lean
+++ b/Mathlib/Data/Complex/Basic.lean
@@ -347,6 +347,8 @@ instance instRatCast : RatCast ℂ where ratCast q := ofReal q
 @[simp, norm_cast] lemma ofReal_intCast (n : ℤ) : ofReal n = n := rfl
 @[simp, norm_cast] lemma ofReal_nnratCast (q : ℚ≥0) : ofReal q = q := rfl
 @[simp, norm_cast] lemma ofReal_ratCast (q : ℚ) : ofReal q = q := rfl
+@[simp, norm_cast] lemma ofReal_ofScientific (m : ℕ) (s : Bool) (e : ℕ) :
+    ofReal (OfScientific.ofScientific m s e : ℝ) = OfScientific.ofScientific m s e := rfl
 
 @[simp] lemma re_ofNat (n : ℕ) [n.AtLeastTwo] : (ofNat(n) : ℂ).re = ofNat(n) := rfl
 @[simp] lemma im_ofNat (n : ℕ) [n.AtLeastTwo] : (ofNat(n) : ℂ).im = 0 := rfl
@@ -358,6 +360,10 @@ instance instRatCast : RatCast ℂ where ratCast q := ofReal q
 @[simp, norm_cast] lemma im_nnratCast (q : ℚ≥0) : (q : ℂ).im = 0 := rfl
 @[simp, norm_cast] lemma ratCast_re (q : ℚ) : (q : ℂ).re = q := rfl
 @[simp, norm_cast] lemma ratCast_im (q : ℚ) : (q : ℂ).im = 0 := rfl
+@[simp] lemma re_ofScientific (m : ℕ) (s : Bool) (e : ℕ) :
+    (OfScientific.ofScientific m s e : ℂ).re = OfScientific.ofScientific m s e := rfl
+@[simp] lemma im_ofScientific (m : ℕ) (s : Bool) (e : ℕ) :
+    (OfScientific.ofScientific m s e : ℂ).im = 0 := rfl
 
 
 /-! ### Ring structure -/